This project has established a population-based registry of children with cerebral palsy (CP) born 1983-1985 in four San Francisco Bay Area counties. Within that population-based study, we are undertaking a number of case-control studies, using controls randomly selected within major birthweight groups, approximately 2 per case. Elements completed in this fiscal year include: ( a) study of in utero exposure to magnesium sulfate in children born weighing <1500 g (very low birthweight, VLBW), finding that whether administered for maternal preeclampsia or in an effort to halt preterm labor, magnesium was associated with a marked reduction in risk of cerebral palsy (CP). A new case-control study of births 1988-1992 in northern California has been designed to examine this association in greater detail, and a feasibility study for a randomized clinical trial (to be supported by a private foundation) was designed and accepted by the IRB of the proposed center, and is scheduled to begin accepting patients in mid-summer, 1995. The NEB has participated in the design of these two new studies and will participate in analyses and publications. (b) A study of prenatal and perinatal risk factors for CP, finding that primigravidity, close pregnancy spacing, delivery in community level hospitals, and birth soon after mother's admission to hospital were associated with increased risk of CP, preeclampsia (in the US usually treated with magnesium) with markedly reduced risk. Birth in a level one facility within three hours of admission was observed in 24% of VLBW children and in no VLBW control. Chorionitis was associated with CP risk only in children who experienced neonatal seizure,and this combination was observed in 14% of VLBW children with CP (in 25% of those with spastic diplegia) and in no control. Re-analyses with CART and logistic regressions are underway. (c) We have recently completed the first study in a defined population to examine specific fetal heart rate patterns in labor, as recorded on electronic fetal heart rate monitoring, as a possible risk factor for CP, and to consider potential confounders. We observe that multiple late decelerations and decrease in beat-to-beat variability, but neither bradycardia nor tachycardia, was associated with increased risk of CP. That relationship persisted after consideration of five other important risk factors for CP. However, positive predictive value was very low. Manuscript has been completed. (d) Data concerning twins from the California project have been merged with nine other population-based datasets on multiple gestations for a study of neurologic morbidity in multiple births, described elsewhere. A variety of other substudies are underway in this data set.